Thursday, August 02, 2012

Dr. Weil: "Whole Soy Foods, In Moderation, Are Very Beneficial"

Dr. Weil posted this video on his blog yesterday. It's everything I believe about soy in less than 5 minutes. This is something Weil does well - condense, consolidate, and communicate in a conversational way.

Some highlights:

Reduce the amount of animal food you eat, that doesn't mean becoming a vegetarian.

I think he could have stressed the moderation part a little more. If you eat a lot of soy you should probably take an iodine supplement, or eat some kelp:
If You're Eating Soy, Make Sure You're Getting Enough Iodine

“Don’t eat,” as in never? Or “don’t eat” as in consume in reasonable or measured amounts? There is a difference.

Also, in context, what’s worse? Habitual consumption of meat in diet or habitual consumption of meat analogues that offsets or displaces meat? Sure, we can discuss eschewing meat and meat analogues entirely, but there’s an argument to be made that mock meats serve a purpose in satiating a cultural desire for familiar animal products that some people (vegan or otherwise) may want to satisfy without eating animals. If there’s little risk, than this shouldn’t be a problem.

Dr. Weil said,“A lot of the products, if you look at the ingredients it will say soy isolate, or isolated soy protein, those are fractioned elements and of soy and we have no epidemiological evidence about their safety or benefits. I would advise avoiding products made with those things and that included a lot of those fake meats that are out there, you know fake hotdogs and lunchmeats, all things made with soy isolate.”

The bolded statement is incorrect.

There is indeed epidemiological evidence about the safety and potential benefits.

Before I get into that however, even if there was no evidence either way, the general amount of health alarm regarding meat analogues is unwarranted and parallels the general anti-soy fear, uncertainty, and doubt, for reasons that I’ll offer has far less to do with health and more to do with a cultural challenge of worldview, but that’s a separate discussion. And I’m not accusing anyone of anything here; it’s just a matter of why soyfoods in general are disparaged in the West.

“We have no evidence” means “we have no evidence,” not, “this is inherently unhealthy.” Sure, we can reasonably speculate that fractured foods tend to associate with negative health outcomes, but we don’t have to rely entirely on such speculation in this instance because we do indeed have good data that I will describe in my next comment, then provide a source in the following comment.

Loma Linda California’s largely vegetarian Seventh Day Adventists (SDA) have been confirmed by National Geographic’s Blue Zones research to be the longest-lived people in North America and are included in a select grouping of the longest-lived, healthiest people on the planet. The Blue Zones goal was straightforward; find hotspots with the highest amount of documented centenarians. It wasn’t based on projection on risk factors or speculation about primitive peoples or measurements of values in lab of either humans or rats administered temporary diets or supplements.

I mention the Blue Zone up front because, aside from the denigration of nutritional science and epidemiology as a means to promote alternative nutritional opinions, there’s a thread of Internet conspiracy-mongering that the SDA data is bogus because they are cooking the books in order to promote their religious agenda. A possibility, everyone has an agenda and bias. But sorry, there have been more then enough credential outside scientists and researchers at this point to confirm the legitimacy of the data. National Geographic is a recent third-party who doesn’t seem to have any agenda or motivation to deceive.

Not only do SDA consume soybeans, soy products (traditional or otherwise), and meat analogues, they have pioneered the industry that makes them. We don’t have to assume that SDA consume their own products, we know that they do. Sure, we can still debate dosage, but the SDA certainly consume soy products of all sorts and it doesn’t appear to negatively impact their health in any significance. It either helps, does nothing, or generally is still up for further investigation. There’s very little evidence as to real world danger from consumption.

Also, we know that among the SDA, the vegetarians fair slightly better than their meat-eating counterparts. This is an apples to apples comparison: a group of people in the same cultural milieu, living in the same geographic area, with similar lifestyles (no smoking or drinking), but while there’s a baseline healthy pattern of eating, there is enough variation to make meaningful comparisons. It’s as close to a real world long term controlled lab conditions as we can get.

SDA meat-eaters consume meat from once to about three or four times a week and would probably be considered semi-vegetarian by most people. Even in comparing meat diets to vegetarians, the long-lived SDA meat eaters still eat comparatively low amounts compared to many Westerners.

Also, SDA are a heterogeneous population with some ethnic diversity, unlike other Blue Zones groups that are far more homogeneous and may have inherited genetic advantages to their diet. Finally, SDA don’t live in some far-flung corner of the world where it would be extremely difficult for an American to emulate their less developed lifestyle.

I’ll provide the American Journal of Clinical Nutrition link to offer a summary of the source I’ll reference and establish that this isn’t some goofy manifesto written by some hack with an agenda. Unlike the author of a certain “popular” anti-soy book whose credentials are fringe and who holds position in a certain alternative nutrition political group.

Unlike the author of a book of propaganda, Gary Fraser’s language is measured, his credentials are legit, and he attempts to offer as unbiased an account as possible, while acknowledging the limitations of the data. I have no idea if he follows a plant-based diet himself, though if he’s compelled to adopt the data he’s collected, it would make sense.

I’ll pull a few quotes in the next comment to back up my statements and I’ll have them run long to retain as much context as possible, emphasis mine.

Diet, Life Expectancy, and Chronic Disease: Studies of Seventh-Day Adventists and Other Vegetarians by Gary E Fraser (2003)http://goo.gl/xACsD

Page 2-3“Although [Kelloggs] is not now an Adventist business, it certainly began as such, and the same motives… have led to the organization of several other well-known health food companies that are, or until recently have been, owned by Adventists. These companies include Loma Linda Foods, La Loma Foods, Worthington Foods in the United States; Granose Foods in the United Kingdom; and, perhaps most prominent, the Sanitarium Health Food Company in Australasia, where Weetbix, Marmite, and peanut butter are national staples. Besides producing breakfast foods, many of these companies have also specialized in plant-based protein foods and drinks, using soy, wheat gluten, and peanut proteins.”

Page 96“Soy milk may protect against prostate cancer. Many soy products contain high levels of genistein and daidzein, which are isoflavones that have weak estrogenic activity. An evaluation of the relative risk of prostate caner among Adventist soy milk drinkers produced interesting results (see Fig. 6-3) (Jacobsen et al., 1998). Those who consumed soy milk more than once daily were substantially protected against prostate cancer (relative risk, 0.3; 95% confidence interval, 0.1-0.9; p = .02). Although the numbers of cases in the high-consumption soy milk subgroup were very small, the effect remained even when it was adjusted individually for the intake of a wide variety of other foods and possible risk factors. The only other prospective study of a soy product and prostate cancer is of Japanese men in Hawaii: those who ate tofu (a soy product) five or more times per week had a relative risk of 0.4 (95% confidence interval, 0.1-1.4), when compared with others (Severson et al., 1989). These provocative results need further support.”

Page 103“The results of multivariate analyses, adjusting for age, sex, past smoking habits, and use of meats (where appropriate), are shown in Table 6-3. As can be seen, despite the wide confidence intervals, many of the effects are apparently quite dramatic. It appears that greater intakes of legumes, dried fruits, and vegetarian meat analogues (usually based on soy, nut, or gluten protein) may have a protective effect. It is interesting that the apparent elevation in risk for those who eat more meat (see model 1 of the table) is probably explained by the meat-eaters smaller intake of important vegetable foods rather than the meat itself. When the plant-based foods are included in the statistical model, the apparent effect of meat disappears completely (relative risk, 1.00 in model 2 of the table).”

Page 270“Those who wish to reduce cancer risk by identifying specific foods to include or avoid, without taking a broader approach to dietary change, will have a difficult time finding conclusive evidence to guide them. However, suggestions would be to increase the intake of legumes, fruits, tomatoes, and soy products and to decrease the consumption of meats. There are no known hazards associated with such choices, and probably several of these changes will finally turn out to have been beneficial.”

Page 271“Within the Adventist population, vegetarian men live longer than their nonvegetarian counterparts by 2.1 years, and for women the difference is 1.8 years. This is despite the fact that the nonvegetarian Adventists eat meat only three times weekly on average.”